5-(tert-Butoxycarbonyl)-4,5,6,7-tetrahydrothieno[3,2-c]pyridine-2-carboxylic acid

110-54-3

24424-99-5

116118-98-0

165947-48-8

4,5,6,7-tetrahydrothieno[3,2-c]pyridine-2-carboxylic acid (7.6 g) was used as a raw material and dissolved in DMF (75 ml). Subsequently, di-tert-butyl dicarbonate (9.6 ml) was added to the solution and triethylamine (5.8 ml) was added dropwise to the mixture. The reaction mixture was stirred at room temperature for 3 hours. After completion of the reaction, water was added and the reaction mixture was acidified with 1N hydrochloric acid. The acidified mixture was extracted with ethyl acetate. The organic layer was washed with water and dried with anhydrous magnesium sulfate followed by evaporation to remove the solvent. Hexane and a small amount of ether were added to the residue and the precipitated crystals were collected by filtration to afford 5-Boc-4,5,6,7-tetrahydrothieno[3,2-C]-pyridine-2-carboxylic acid (9.36 g, 80% yield). The product was confirmed by 1H-NMR (CDCl3): δ 1.49 (s, 9H), 2.90 (brs, 2H), 3.74 (brs, 2H), 4.51 (brs, 2H), 7.56 (s, 1H). Mass spectrometry analysis (SIMS) showed m/z: 284 (M++1).